Transcriptional control of rohon-beard sensory neuron development at the neural plate border

Rohon-Beard (RB) mechanosensory neurons are among the first sensory neurons to develop, and the process by which they adopt their fate is not completely understood. RBs form at the neural plate border (NPB), the junction between neural and epidermal ectoderm, and require the transcription factor prdmla. Here, we show that prior to RB differentiation, prdmla overlaps extensively with the epidermal marker dlx3b but shows little overlap with the neuroectodermal markers sox3 and sox19a. Birthdating analysis reveals that the majority of RBs are born during gastrulation in zebrafish, suggesting that it is during this period that RBs become specified. Expression analysis in prdmla and neurogeninl mutant and dlx3b/dlx4b morpholino-injected embryos suggests that prdmla is upstream of dlx3b, dlx4b, and neurogeninl at the NPB. mRNA for neurogeninl or dlx3b/dlx4b can rescue the lack of RBs in prdmla mutants. Based on these data, we suggest a preliminary gene regulatory network for RB development.